Existing drug could hold the key to preventing breast cancer in pre-menopausal women

A new study has shown that an existing drug used by the NHS could be repurposed to prevent breast cancer in pre-menopausal women.

Researchers at the Manchester Breast Centre, based at sites across Manchester including Wythenshawe Hospital’s Nightingale Centre – part of Manchester University NHS Foundation Trust (MFT) – found that blocking the effects of the hormone progesterone, using an existing drug called ulipristal acetate, may reduce the risk of breast cancer developing in women before the menopause.

The study was funded by Breast Cancer Now, and supported by Prevent Breast Cancer who are based at the Nightingale Centre – Europe’s first purpose-built breast cancer prevention centre which is based at Wythenshawe Hospital.

Several of the authors were supported by the MFT-hosted National Institute for Health and Care Research (NIHR) Manchester Biomedical Research Centre (BRC).

Progesterone is a hormone that has been found to promote the growth of a type of breast cell that has the potential to develop into breast cancer. The hormone also impacts the environment inside the breast, making it easier for healthy cells to become cancerous. Blocking the effects of progesterone could be a new way to stop breast cancer before it starts.

Clinical lead author, Dr Sacha Howell, Clinical senior lecturer at The University of Manchester, Director of Manchester Breast Centre and Consultant Oncologist at The Christie and MFT said:

We are profoundly grateful to the women who volunteered for this study. Our research, with them, provides evidence that progesterone plays a critical role in breast cancer development in high-risk individuals. By targeting its action, ulipristal acetate and other anti-progestins show promise as preventive treatments for women at increased risk.

“What makes this study particularly exciting is the combination of clinical imaging and biological analysis, which gives us a powerful tool to understand how prevention therapies work at both the tissue and molecular levels. These results lay important groundwork for larger trials to confirm the potential of anti-progestins in reducing breast cancer risk”.

As part of the study, 24 women aged 34-44 with a family history of breast cancer took ulipristal acetate for a 12-week period. During the trial, they underwent breast biopsies, blood tests, and detailed Magnetic Resonance Imaging (MRI) scans before and after treatment.

The scans showed that the breast tissue became less dense with treatment – which encouraged researchers as high breast density can lead to a greater risk of breast cancer.

The study also showed that taking ulipristal acetate helped block the growth of luminal progenitors, breast cells that can turn into cancer. Researchers also observed dramatic changes in breast tissue, with the treatment reducing the stiffness of breast tissue and making the environment less favourable for cancers to develop and grow.

The study concluded that using ulipristal acetate reduces the risk of breast cancer by altering breast tissue in a way that makes it harder for cancer cells to develop and grow. The impact of this study could reduce the need for women at high risk of developing breast cancer to undergo invasive preventative treatment.

Grace Burton, 27, from Bromley, Greater London, underwent a preventative double mastectomy last year after finding out she was at high risk of breast cancer due to an inherited BRCA1 gene change at the age of 21.

Grace says: “Breast cancer has had a huge impact on my family – both my mum and my aunt were diagnosed, and knowing I was at high risk was always in the back of my mind. Having later gone through preventative surgery myself, I know how heavy and difficult those decisions can feel. That’s why this new research into preventative medication is so exciting, it offers hope for other women who might one day have less invasive options to protect their health.

For those of us with a strong family history, the possibility of preventing breast cancer before it starts is incredible. It gives me hope that future generations may not have to make the same tough choices and can grow up with more options and less fear around breast cancer.